A reversing valve of the above type is disclosed in DE 34 16 336, wherein there are two opposed valve seats, between which is slidably disposed an armature provided with seals.
The armature is slidable in a guide tube having a wall facing the armature provided with longitudinal recesses or grooves to provide fluid flow passageways between the channels. The portions of the guide tube between the longitudinal recesses serve for guiding the armature in its slidable movement.
An electromagnetically actuated valve of a different type is disclosed in DE 37 16 072, in which the armature is configured with a valve sealing part movable in a guide borehole, through which a fluid passes. For this purpose, the valve sealing part comprises a cylindrical base unit having a smooth outer surface which forms passages for flow of the fluid.
In electromagnetic reversing valves, there is need to minimize the reluctance of the magnetic circuit consisting of a yoke, a pole tube and the armature, i.e., minimizing the iron-free spacing between the structural parts.
The arrangement in DE 34 16 366 doesn't meet this criteria, since the recesses extending in the longitudinal direction of the armature guide tube form part of the iron-free gap. The construction in DE 37 16 072 in which smooth surfaces are provided for the formation of fluid passages increases the iron-free gap between the armature and the pole tube if applied to the type of valve according to the invention.